Short is fine, but at the moment it's so short that I'm more confused than interesting. After a few wikipedia readings, all I can say is that it's an anomalous 2010 TK7 that hasn't crashed yet. Where did it come from? Is it going to crash into us? Why do the aliens blame us? It lacks uniqueness (since it's based on a couple of real things with a real incident and not much is changed other than random growing and aliens), and it lacks story. So far the scip is actually too long to keep my interest considering the hook is so weak.

I'm a bit confused about what you're saying here. You say it's too short to make any sense at all, but you also say its too long because the hook is bad. Assuming my hook continues to be bad, would it be sufficient to cut out all the addendums and make the description and special procedures, say, 6 lines apiece?

Also, do I understand you right that using a retcon for real stuff is not a good idea? I'll be sure to avoid anything like that then. Perhaps I should use a vulcanoid instead, because I know those don't exist.

Using the Earth trojans is fine, and I don't think that retcon means what you think it means. Retroactive Continuity only applies to fictional timelines. Real life doesn't have continuity to retroactively change, and it is impossible to change the past anyway (the real world equivalent is historical revisionism). Retcons are basically only possible on this site within a series or canon, because of the "no canon" canon.

Any way the Earth trojans are a place and you should feel as free to use them as you would Los Angeles or Antarctica or Pangea or whatever.

The actual anomaly isn't plainly stated in the description, and there's no reason it shouldn't be.

The premise of this is so sketchy that I don't really see how you could ever get it. Theia doesn't exist anymore, so this object isn't Theia, it just thinks it is. An anthropomorphic asteroid with delusions of planethood is such a surreal concept that it doesn't really suggest itself out of the SF elements you've used here.

Why is it mollified only with lunar regolith with high He-3? What does He-3 have to do with anything?

The moon has a fair amount of He-3 because it doesn't have a magnetosphere or an atmosphere; any dead rock this close to the sun for billions of years is going to get some, including the Earth trojans.

The plan for the SCP is to rebuild itself into Theia because "we had it first". But I can see how it would be difficult to make the link.

I think the big leap here is to anthropomorphic asteroid, and then to Theia. Again though it can't "rebuild" itself into Theia; Theia simply doesn't exist anymore, not even in pieces, all the matter that made Theia hit mixed with the matter of proto-Earth to make the current Earth, and the two proto-Moons.

I know. The plan is for the asteroid to pull/teleport/move the pieces (yes, even that stuff mixed with Earth system matter. You can't destroy atoms) of what used to be Theia into the SCP, recreating Theia. However, as you suggest, this is most likely too much of a leap. If the SCP succeeds in its plan and the Foundation does nothing about it, then both the Moon and Earth will be dead husks with lots of seismic instability. I tried to pull in the strong earthquake idea to show what would happen when the SCP pulls some material out of Earth, but it is clear now that that was a bad approach. Although the wreckage my SCP would cause would probably be grounds for a Keter SCP, this article says attempting a Keter at this time is an extremely bad idea. Therefore, even if I somehow fix the Theia concept, I'm still at an impasse.

There's also the possibility, if the Theia recreation idea is doomed, that I could pull in Theia from an alternate timeline/universe/dimension/whatever and try to do something interesting with it. However, that would violate the common pitfall of using alternate dimensions.

Meh, if it is Keter it is Keter. Most space objects are Keter, both because of the difficulty in containing something that can be observed from Earth and because of the scale of destruction of even mundane interactions between astronomical objects. The guide is more of a caution against deciding to write a Keter object, and not against writing an object that happens to be Keter.

I think your biggest problem is getting us to believe in anthropomorphic sapient space rocks, once you figure out how to do that the rest should be easy. It can just say it thinks it is Theia.

My point about it not being Theia is that 2010 TK7 has as much a claim to being Theia as does a rock in my garden. Which is fine, deluded sapient space rocks are best rocks.

An alien civilization specializing in terraforming is based on Theia. The civilization knows that they are going to slam into Earth, and they aren't advanced enough to simply mass evacuate the planet. In desperation, they launch a probe into space. This probe is successfully placed where the aliens want the restored Theia to be, and a few aliens leave with the probe to colonize Theia when the probe is done. Unfortunately for them, (and fortunately for the humans) the probe lost most of its power as fuel to remain a trojan of the new Earth. In order to regain the power needed to restore Theia, it uses solar panels to recharge. Of course, all the aliens waiting for Theia end up dead since there are no habitable planets for them anymore and the probe won't finish in their lifespan.

Fast forward to the Foundation era. The probe has successfully acquired enough energy to restore Theia, but wear and tear has slowed down the rate of material collected and shaped per year considerably - the probe can currently restore only 1,000 kg/year; however, the rate is increasing because the probe is using energy from the Sun and thermal energy from the material collected to repair itself. The probe (now the asteroid 2010TK7), learning how to communicate via radio waves from Earth, sends the Foundation an ultimatum: Either the Foundation hands over the requested mass of Earth or Moon material each year, or the probe will take the material by force. The probe demonstrates its abilities by taking some material somewhat below the Earth's crust, causing a sinkhole. The Foundation complies with the probe's request. As material is being sent to the probe, the Foundation notices several structures nearby that don't resemble asteroids. The probe says that they are the remnants of the residents of Theia (or as it says, "my creators"), and says that they died when the probe couldn't restore Theia. The probe says that it is its duty to restore the planet for its creators at any cost. Not wishing to antagonize the probe and jeopardize the current non-aggression deal, the Foundation deposits the material and leaves peacefully.

Why did they chose an object in an unstable orbit to xenoform in the first place instead of Venus, Earth or Mars? Why did they attempt to colonize a system as young and chaotic as ours was? Why didn't they attempt to xenoform the Earth after it formed post-collision instead of trying to rebuild a planet? How does the probe add mass without violating conservation? If it is teleporting mass from the Earth and Luna, why couldn't they teleport the colonists?

The solar constant. If the Theians were to move the new planet somewhere else, the colonists won't get the heat needed from the Sun. This is referred to as the "Goldilocks zone". Utilizing the third dimension might make a good compromise, however.

The Theians started on Theia. Also, other planets (and other systems) are extremely far away; the Theians might as well stay put and wait for the probe to do its job.

There were only a few Theians left after the collision; most of them died with Theia. The only terraforming tech left was with the probe, and it didn't have enough power to fix Earth either. When it did have power, the Theians were all dead.

Teleporter.

The teleporters will kill living things. The teleporters don't move material all at once; it moves sections of the material until it is all at the destination. The problem with living things is that living things need nearly all of their material, such as brains or hearts, to live.

1. Earth and Mars are in the Goldilocks zone. Theia probably wasn't (at least not consistently). Why pick Theia as the colony site?
2. Are you saying they are native to Theia? That's really implausible. Less than 100 million years is not enough for life to evolve, much less an advanced technological civilization. Theia and proto-Earth were both still Hadean and inhospitable. If they were native why were they xenoforming Theia? If they weren't natives then how was Theia any closer than Earth or Mars? Also they had tech for buliding planets but not interplanetary space travel?
3. My problem is that current Earth is also Theia so if the probe was supposed to xenoform Theia why did it pick the tiny chunk that is 2010 KT instead of the huge planet that was right there as the new Theia?

I suppose that's fair. The newer Theia could be made between Mars and Earth.

I see your point here. Perhaps this revision will fix those issues:

First, let's say that Theia was less massive (but still arguably close to) the mass of Mars. Let's say that the Theians did come from outside the Solar System on a sleeper ship. When they arrived, they were close to Theia. They chose Theia over Earth and Mars because the Theians cannot withstand their gravitational pull; it's similar to the reason jet pilots have trouble with G-forces. Theia; however, had the best option with gravitation, especially since the bigger Earth was eating up other space debris (sort of like Earth's protection by Jupiter). They xenoformed Theia because, as you said, inhospitable initially. They technically could do space travel, but they had to set down roots because fuel was too limited to try another solar system. Also, there were g-force and speed of light/special relativity concerns with moving again, not to mention the many micrometeroids during the Hadean. I suppose it can be assumed that the Theians terraformed Theia while they orbited the planet, then settled. Presumably, they had a small defense network to prevent meteors from slamming into the planet (except for the big one, Earth). Furthermore, xenoforming and such is still bounded by the speed of light - the teleporters aren't instantaneous.

The probe didn't want all that Earth + Moon stuff on its precious Theia. Also, it had the more practical gravitational concerns to consider for the Theians.

Theia, a Hadean in an unstable orbit of a star that is only about a 100 million years old, is just such a terrible colony candidate that I can't imagine anyone actually choosing it unless something went terribly wrong. The extent of the error has to involve not only the wrong planet, but the wrong system entirely, and also somehow an attempt to set up a colony on a molten rock with a reducing atmosphere that was barreling towards another planet. The colony was doomed long before the collision, it was doomed when they launched centuries or whatever before.

However, if you're a species that prefers highly dense, highly energetic environments (such as the center of a planet), but have technological difficulty inserting yourself into such an environment in other solar systems, but know how to survive the heat and density of impact, then Theia becomes a great colonization candidate. You land on the planet and let it crash into Earth, inserting the colony deep into the mantle of the larger world.

Yeah, that's what I was getting at. The disconnect here for me is the idea they would want to "rebuild" Theia in Earth's L7 in the environment of the current solar system. If Hadean doomed Theia was a good place to live for them then, they wouldn't be trying to build a Garden Theia now.

In your scenario, they should be happy as lava clams in Earth's mantle.

Huh. I didn't think of that idea. There's a few notable questions I have on it, so what I come up with isn't deemed implausible:

Isn't it implausible for the Theians to survive the collision? Theia was completely disintegrated into some Earth debris and some rings. Most of the Theian population would have most likely ended up dead due to the low density of rings, exposure to a vacuum, blunt trauma from the collision's kinetic energy, and possibly being flung from the collision.

There's also a question I have about the lunar Theians. Since the Earth Theians have a lot more hot and dense territory than Theia and the Lunar Theians do not, would it be fine to depict the Lunar Theians as having envy of the Earth Theians, and thus a demand for "Theia as it was"? I suspect that this might make for an interesting Theian civil war story, with the Foundation and Earth in the middle of the fight. There could also be a third faction of Theians that were flung into space.

First, the lunar colony, should it exist, would likely consider Venus to be a more desirable homeworld. If I understand the temperatures right, Venus is considerably hotter than Io, which also means more yummy food for the Theians.

Secondly, and this may seem novice, but shouldn't there be more conflict for the SCP, thus making a story? Currently, the Earth Theians couldn't be happier, and the Lunar Theians will be happy when they go to Venus/Io. Possible conflicts I can see are "We want more Earth on the Moon so we can be hotter"/"But I want to go to Venus too!"/"Those Earth Theians are messing with our tectonic plates"/"The Lunar Theians want to smash into us so they can join their counterparts on Earth and make Earth even hotter".

With this idea, would the article name be changed from "Theia" to "The Theians", since the focus is now on the people instead of the planet (which is absolutely destroyed)?

What exactly would be the best way to show to the Foundation that they are actual Theians instead of a mysterious creature or just a tectonic plate anomaly? Should they tell the Foundation (roughly, using learned UTF-8) "We deliberately slammed into your planet so we can have more heat. Sorry about the inconvenience."

Would it be plausible for the Lunar and Earth Theians to evolve differently over time? Should these different species have -1 and -2 appended to their SCP designation?

Geological activity is heat. If they want to live in the mantle of the Earth primarily, to the extent that they crashed two planets together to get there, then they probably want to live in environments that are more like that, then not.

Yeah I was suggesting that maybe the inside of Io is better than the inside of the moon. I don't know if it would be better than the inside of Venus, but if the need an environment with convection currents in mantle it might be.